The main goal of this proposal is to investigate whether oxidative stress and apoptosis of cavernous tissues are major pathways in erectile dysfunction. We will also investigate whether inhibition of oxidative stress and apoptosis can restore erectile function. The rationale for this project is that erectile dysfunction affects about 30 million men in the United States and more than 200 million men worldwide. Based on our preliminary data and prior publications, we hypothesize that apoptosis of cavernous tissues are down stream events in erectile dysfunction. We further hypothesize that anti-oxidative agent or Bcl2 gene therapy can restore erectile function in animal model. We will test these hypotheses through the following experiments: Specific Aim# 1. To test the hypothesis that diabetes-induced erectile dysfunction is due to apoptosis of cavernous tissues. Under this specific aim, we will analyze erectile function in diabetic rats and then analyze apoptotic index, anti-apoptotic genes, pro-apoptotic genes, cytochrome c, superoxide dismutase and smooth muscle differentiation markers. We will also investigate whether an anti-oxidative agent (TEMPOL) can restore erectile function in diabetic rats. We will use the following techniques: RT-PCR, real-time RT-PCR, in situ hybridization, immunohistochemistry, electro-stimulation of cavernous nerve for pressure measurements, gene delivery, histology, light and electron microscopy. Specific Aim # 2. To test the hypothesis that insulin treatment can restore erectile function through restoration of anti-apoptotic factors in cavernous tissues of diabetic rats. Under this specific aim, we will treat diabetic rats with insulin and then investigate whether erectile function is restored through restoration of anti-apoptotic pathways described under specific aim # 1. Specific Aim # 3. To test the hypothesis that gene therapy with the Bcl2 anti-apoptotic gene can restore functional, cellular and molecular mechanisms of erectile dysfunction in diabetic rats. Under this specific aim, the Bcl2 gene will be transfected into the cavernous tissue of diabetic rats using an adeno-associated virus vector. We will do the following experiments: (a) Functional assessment of the effects of Bcl2 gene therapy on penile erection in diabetic rats, (b) Analysis of the effects of Bcl2 gene therapy on the oxidative stress pathways and the apoptotic pathways described under specific aim 1. (c) Analysis of the effects of Bcl2 gene therapy on the expression of smooth muscle markers in diabetic rat penis. This proposal is novel because oxidative stress and apoptotic pathways in diabetes-induced erectile dysfunction have never been investigated. Accomplishment of these experiments will provide novel molecular mechanisms of erectile dysfunction and can help guide us towards the development of new therapies for the treatment of erectile dysfunction.